<!DOCTYPE html>
<html light>

<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title></title>
    <style type="text/css">
    :root {
        --color1: teal;
    }

    h1 {
        background-color: var(--color1);
        cursor: pointer;

        transition: all .5s;
    }

    h1:hover {
        background-color: color-mix(in hsl, var(--color1) 100%, black 30%);
        color: white;
    }
    </style>
</head>

<body>
    <h1>你好忙的</h1>
</body>

</html>